This is the three four time signature.
It tells you that there are three beats in each bar.
There are three quarter notes in one bar of ^ time.
Three four time is also known as waltz time.
A dot after a note extends its value by half.
A dot after a half note means that you hold it for three beats.
One dotted half note makes one bar of music in ^ time.
A good way to become familiar with any new note or rest value is to combine it with other note values and clap the rhythms. Here is an example using dotted half notes in ^ time along with quarter notes and half notes. Clap the rhythm and count out loud.